Hot Rod

Mike Dunn

I can help you out with this if you'd like. I have experience with OWB interfacing with all kinds of radiant applications. just shoot me an email with the details. I would like some practice on the consulting side of the business (free of charge of course)

Mike

mike@dunnplumbing.com

Bob Forand

Hot Rod

Can you help me more on the wood boiler to buderus. I am stuck on how to control the boiler and pumps. I understand the piping, but unsure of controlling it.

hot_rod

It will depend on

your final piping arrangement. Two boilers with parallel piping is pretty straight forward. With the wood as primary heat, a aquastat would "watch the loop temperature. Better yet a differential control. As the loop falls below a temperature, the Buderus fires.

Remember wood boilers are very interactive. They need to be started and "tended" by the owner. There output is quite variable depending on how often you "poke" or arrange the fire. The type of wood, how dry it is, how you stack it in the fire box, etc are all part of wood burning. I doubt you will ever have a 100% automatic system with wood fired devices

I find you need to look at and work the fire every couple hours. it's not a light up once a day and walk away type of appliance.

I like to pipe wood boilers with some buffer. 500 gallons or so. Then with primary secondary piping you can run the wood hot and fast, the most efficient burn. If the building is not at design, full load condition the buffer tank gets some of the energy. When the load is satisfied, the tank gets full wood output.

This allows some "parking space" for the wood fired BTUs. It allows an overheat space. But most importantly it allows for some coasting time. Heat is available from the buffer without firing the wood.

Controls for that are a bit more complicated.

Here is my latest idea. I think I can clean up the 5 controls I now use into two, possibly one solar differental control.

First off the wood boiler circ turns on when the boiler reaches 65C. It has a built in snap disc switch to handle this. it's a poor mans return protection device. Simple and effective.

The boiler to primary circ P4 is controlled by a differential control. When ever the boiler is 10F warmer than the loop it fires. It's the Watts Radiant prototype solar control.

The primary loop to system or load circ P1 is also on a differential control, tekmar 155.. The Solar Phoenix (your Buderus) runs off it's internal aquastat.

A Goldline setpoint control fires the buffer tank circ. It charges when the loop is above 140. If the wood can't maintain the load and the buffer, it drops the loop temperature and full fire goes to the radiant.

My only head scratcher is unloading the buffer. I want two different controls to run that circ. I believe a differential control with a triac will allow me to put voltage from another control against it. If not an isolation relay would disconnect the setpoint output from the buffer differential control, so either or could run the buffer. So if the fire is out, but the buffer is warm, then a differential control would unload the buffer.

So I need 3 differential controls, and one setpoint. I believe such a control is out there, possibly that Resol E control. If not two solar controls with dual outputs and with the thermostatic function should work.

hr

World Plumber

Why make a mountain out of a mole hill. If everything is working the way it is piped leave it alone. Pipe your heat exchanger in one side of the boiler and out of the other side. Set your pump to circulate if the wood burner is hot or constant circ. This will maintain temp in the Bodaris. Let the existing system control the heating from the hot boiler. Set the aquastat on the Bodaris lower that the temperature you are keeping the wood boiler. Your all set with a self controled system. I have 8 of them hooked up this way on problems.

hvacfreak

higher / lower

And the JCI A350P works great for this stuff ( proportional with remote bulb...gotta love it ). And they just look cool.

http://cgproducts.johnsoncontrols.com/default.aspx?main.aspx&2

Sadly , a well tuned pneumatic system is the ideal if only the time and the means. - Peace